Human-Machine Interface Apparatus with Expanded Function

1. A human-machine interface apparatus for inputting information to an automation device, comprising: a panel device replaceably mounted on a control panel of the automation device, the panel device including; a first key unit arranged on a front surface of the panel device for a user to input instruction; a printed circuit board (PCB) arranged on a back side of the panel device, including: an expansion interface; an output interface for connecting to the automation device; and a controller electrically connected to the first key unit and the expansion interface; a LCD screen arranged on the front surface of the pane device, and electrically connected to the PCB for displaying information sent from the PCB; a second key unit fixedly arranged on the automation device and electrically connected to the expansion interface for providing additional input function; and a nameplate arranged beside the second key unit, wherein the controller receives input from the first key unit as well as controls the expansion interface to receive input from the second key unit, and the input from the second key unit performs all input functions of the first key unit, and wherein functions of the second key unit are shown by the nameplate.

2. The human-machine interface apparatus as in claim 1 , further comprising a protection circuit electrically connected to the expansion interface, the controller and the first key unit.

3. The human-machine interface apparatus as in claim 2 , wherein the protection circuit is a relay.

4. The human-machine interface apparatus as in claim 2 , wherein the protection circuit is a fuse.

5. The human-machine interface apparatus as in claim 2 , wherein the protection circuit is a surge protector.